vm: clear exception information before calling managed code functions

If execution in an existing VM that threw an exception was resumed
through uc_vm_call() or uc_vm_invoke(), the exception was never cleared,
causing all subsequent calls to return with an exception status as well.

Ensure that any preexisting exception information is discarded before
executing the requested function in order to start from a clean state.

Signed-off-by: Jo-Philipp Wich <jo@mein.io>

1 files changed, 15 insertions, 4 deletions

diff --git a/vm.c b/vm.c
index d5d3feb..2c8f524 100644
--- a/vm.c
+++ b/vm.c
@@ -731,6 +731,18 @@ uc_vm_exception_new(uc_vm_t *vm, uc_exception_type_t type, const char *message,
 	return exo;
 }
 
+static void
+uc_vm_clear_exception(uc_vm_t *vm)
+{
+	vm->exception.type = EXCEPTION_NONE;
+
+	ucv_put(vm->exception.stacktrace);
+	vm->exception.stacktrace = NULL;
+
+	free(vm->exception.message);
+	vm->exception.message = NULL;
+}
+
 static bool
 uc_vm_handle_exception(uc_vm_t *vm)
 {
@@ -765,10 +777,7 @@ uc_vm_handle_exception(uc_vm_t *vm)
 		uc_vm_stack_push(vm, exo);
 
 		/* reset exception information */
-		free(vm->exception.message);
-
-		vm->exception.type = EXCEPTION_NONE;
-		vm->exception.message = NULL;
+		uc_vm_clear_exception(vm);
 
 		/* jump to exception handler */
 		if (chunk->ehranges.entries[i].target >= chunk->count) {
@@ -2358,6 +2367,8 @@ uc_vm_call(uc_vm_t *vm, bool mcall, size_t nargs)
 	uc_value_t *ctx = mcall ? ucv_get(uc_vm_stack_peek(vm, nargs + 1)) : NULL;
 	uc_value_t *fno = ucv_get(uc_vm_stack_peek(vm, nargs));
 
+	uc_vm_clear_exception(vm);
+
 	if (uc_vm_call_function(vm, ctx, fno, mcall, nargs & 0xffff)) {
 		if (ucv_type(fno) != UC_CFUNCTION)
 			uc_vm_execute_chunk(vm);